Hydraulic anchors for tubular strings



y 5, 1954 J. F. DE ROCHEMONT 3,131,769

HYDRAULIC ANCHORS FOR TUBULAR STRINGS 5 Sheets-Sheet 2 Filed April 9, 1962 I NVEN TOR.

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ride 1v 1 DEBOCHEMONT May 5,. 1964 Filed April 9, 1962 J. F. DE ROCHEMONT HYDRAULIC ANCHORS FOR TUBULAR STRINGS 3 Sheets-Sheet 3 INVENTOR.

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United States Patent 0.

3,131,769 HYDRAULIC ANCHORS FOR TUBULAR STRINGS John F. de Rochemont, Houston, Tex., assignor to Baker Oil Tools, 1118., Los Angeles, Calif., a corporation of California Filed Apr. 9, 1962, Ser. No. 186,193 Claims. ((11. 166-412) The present invention relates to subsurface well bore apparatus, and more particularly to apparatus adapted to be anchored in well casing, or similar conduit strings, disposed in well bores.

Anchors for tubular strings have been used in which piston types of gripping or anchoring elements are forced and held outwardly against the wall of the surrounding well casing by hydraulic pressure developed within the anchor itself. Ordinarily, the piston anchoring elements are urged toward retracted position by one or more springs, the hydraulic pressure differential in the tool overcoming the force of the springs and shifting the anchor elements outwardly to embed their wickers or teeth in the wall of the well casing.

The lowering of the anchor apparatus on a tubular string through fluid in the well bore develops hydraulic pressure differentials therewithin, tending to urge the anchor elements outwardly against the well casing. If the elements are shifted outwardly, they slidably engage the casing while the tool is being lowered therein, resulting in dulling of their teeth and a substantial reduction in their holding force against the casing when the anchor is at its setting location in the well bore. To avoid onward expansion of the anchor elements, the use of comparatively heavy retracting springs, or a plurality of retracting springs, has been proposed. Space consideration do not always permit the use of heavy springs, and even where they are used, they tend to limit the range of expansion of the anchor elements and make assembly of the apparatus difiicult. Moreover, the spring force offsets to some extent the hydraulic force holding the anchor elements against the casing, decreasing the longitudinal force that the anchor apparatus can withstand in the well casing.

Accordingly, it is an object of the present invention to provide improved hydraulically operated anchors embodying piston anchor elements, which avoid the use of heavy retracting springs and still hold the anchor elements in retracted position, despite the development of substantial pressure differentials in the anchors resulting from their being lowered through fluid in the well casing. Re-

ention of the anchor elements in retracted position insures against dulling of their casing engaging teeth.

Another object of the invention is to provide an improved releasable retainer device for preventing inadvertent outward expansion of piston anchor elments against the wall of a well casing during lowering of the apparatus through fluid therewithin, the retainer device being positively releasable, when desired, and avoiding interference with expansion and retraction of the anchor elements after being released. When released, the retainer device no longer exerts any force on the anchor or gripping elements, tending to offset hydraulic forces holding the elements against the casing.

A further object of the invention is to provide a releasable retainer device for preventing inadvertent outward xpansion of piston anchor elements against the wall of a well casing, which is releasable hydraulically at a predetermined pressure, and which is economical to produce and easy to assemble. I V

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several forms in which it may be embodied. Such forms are shown in the drawings accompanying and forming part of the present specification. These forms will now be described in detail for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a longitudinal section, parts being shown in side elevation, through an anchor apparatus for a tubular string, with its anchor elements in retracted position;

FIG. 2 is an enlarged longitudinal section through a portion of the apparatus disclosed in FIG. 1;

FIG. 3 is a cross-section taken along the line 33 on FIG. 2;

FIG. 4 is a view similar to FIG. 2 disclosing the anchor or gripping element expanded outwardly against the wall of a well casing;

FIG. 5 is a longitudinal section through a portion of a hydraulic anchor apparatus, disclosing a modified form of apparatus, with an anchor element in retracted positron;

FIG. 6 is a view similar to FIG. 5 disclosing the anchor element expanded against the wall of the well casing;

FIG. 7 is a view similar to FIGS. 2 and 5 of still another form of the invention;

FIG. 8 is a view similar to FIG. 1 illustrating yet another form of the invention, with its anchor elements retracted;

FIG. 9 is an enlarged longitudinal section through a portion of the apparatus shown in FIG. 8, with the piston gripping device in expanded position;

FIG. 10 is a cross-section taken along the line 101 on FIG. 9;

FIG. 11 is an enlarged fragmentary longitudinal section through a portion of the apparatus shown in FIG. 8, with a piston gripping device in retracted position.

An anchor apparatus A is disclosed in FIG. 1, which is adapted to be set against the wall of a well casing B against upward movement therewithin. The specific anchor apparatus disclosed includes a tubular body 10 having a central passage 11 therethrough, an upper threaded box 12 on the body being threadedly attached to the lower end of a tubular string C extending upwardly to the top of the well bore. The lower end of the body 10 may also be provided with a suitable threaded box 13 for threaded attachment to the body of a well packer P, which is adapted to be anchored in packed-oil? condition against the Wall of the well casing, usually to prevent downward movement of the apparatus therewithin. The Well packer P will usually have a suitable packing structure thereon (not shown) for eflecting a seal between its body and the Wall of the well casing, so that fluid pressure can be developed below the well packer, as well as within its body passage 14 and the passage 11 of the anchor body 10.

The anchor body 16 has a plurality of generally radially slidable piston type of anchor or gripping elements 15 mounted in cylindrical bores 16 extending completely through the body wall. Each piston anchor element 15 is adapted to occupy a fully retracted position within the confines of the body 10, as determined by engagement of its inner portion 17 with stop shoulders 18 extending inwardly from opposite sides of the cylindrical bore 16. When the anchor element 15 engages the stop shoulders 18, a longitudinal row of external wickers or teeth 19 thereon preferably do not extend beyond the periphery of the body 10.

When sullicient pressure is developed within the body passage 11, such pressure acts upon the inner face 20 of each button gripping element 15 and urges the latter outwardly to engage its wickers or teeth 19 with the Wall of the well casing B. Such wickers or teeth 19 usually face in an upward direction to anchor the body, as well as the tubing string C and the packer P therebelow, against upward movement in the wall casing. Leakage of fluid around the piston 15 is prevented by a suitable piston ring 21, such as a rubber 'or rubber-like ring, mounted in a peripheral groove 22 in the piston and slidably and sealingly engaging the wall of the cylinder 16.

Each button anchor element 15 is appropriately oriented with its wickers or teeth 19 disposed normal to the axis of the cylinder 16 by an orienting and retainer bar 23 extending through a longitudinal slot 24 ineach element opening through its exterior, the retainer bar. also extending into upper and lower grooves 25 in the body on opposite sides of the anchor element 15. The piston retainer 23 issuitably secured to the body 10, as by use of upper and lower screws 2s. The retainer bar 23 also acts as a seat for one or a plurality of springs 27, which may be helical compression springs, mounted in the longitudinal slot 24, the outer ends of which engage the retainer bar 23, and the inner ends of which are disposed in sockets 28 in the anchor element in engagement with an inner face 29 of the latter. As disclosed in the drawings, two longitudinally spaced springs 27 are mounted in each pistonanchor or gripping element 15. However, one or more of such springs can be used.

The springs 27 urge the anchor elements 15 towards their retracted position. When sufiicient pressure is de veloped in the central passage 11 to overcome the force of the springs, the anchor elements 15 are urged outwardly to engage their teeth 19 with the wall of the well casing B. When such pressure is relieved, the springs 27 return the button anchor elements to their fully retracted position. 7 V

As noted above, during lowering of the apparatus A through the liquid in the well bore, pressure surges, and the like, are developed within the central passage 11, which pressure tend to overcome the compressive force of the spring or springs 27 and urge each button anchor element 15 outwardly so that its wickers or teeth 19 are engaged with the well casing. Such engagement results in dulling of the teeth during lowering of the apparatus in the well bore, the teeth sometimes having insuihcient sharpness to be able to embed themselves in the wall of the Well casing for the purpose of effectively performing an anchoring function, when the setting location is reached. The anchoring function is to prevent upward forcespusually resulting from high pressures developed string C to which the apparatus is secured. In the present instance, the springs 27 are not made heavy, so as to exert a large retracting force for the purpose of preventing inadvertent outward expansion of the button anchors 15. Instead, a releasable retaining or holding device is employed for positively preventing the anchor or gripping elements 15 from being s hifted outwardly until the apparatus has beenlowered to its setting location in the well casing. The retaining elements are then released and thereafter will exert no resisting force tending to prevent outward expansion of its associated anchor elements against the wall of the well casing.

, As shown, the. retaining and holding device includes a releasable retaining'or holding rod 30 disposed coaxially j within each spring 27, the rod having an inner head 31 hearing against the inner face 29 of the anchor element,

and also having a stem 32 piloted within a radial guide bore or 'passage 33 in the retainer rod or bar 23.11ategral with' the stem 32 is a shearable ring or flange 34,

which engages'the inner surface 35 of the retainer bar 23.j

When the ring34 is engaged with this inner surface 35,

is transmitted through the holding rod 30 and its flange 34 to the retainer bar 23. The holding rod 30, therefore, provides a solid strut precluding outward expansion of the button anchor element 15.

During lowering of the apparatus A through the fluid in the well casing B, pressure dilferentials that might be developed in the body passage 11 are insufiicient to overcome the shear strength of the integral shear ring or flange 34 on each of the holding rods 30, and as a result, such pressures are incapable of shifting the anchor elements 15 outwardly against the well casing B. In fact, they are incapable of any material outward shifting of the anchor elements, the wickers or teeth 19 of the latter remaining within the perimeter of the body 16 of the tool, and, therefore, not susceptible to contacting the well casing, which might produce their dulling. When the location of the well casing is reached at which the anchor elements 15 are to be expanded outwardly, the lower packer P is set in packed-oil condition in the well casing, in a known manner, whereupon the application of pressure to the fluid in the tubular string C and central passage 11 of the body 10 of a sufficient value will overcome the shear strength of each flange 34 and disrupt it, which will remove the restraining or holding force of the rod 30 maintaining the anchor element 15 in its retracted position.

The pressure is then effective to shift the anchor element '15 outwardly against the compressive force of its return springs 27, to embed the wickers or teeth 19 in the wall of the Well casing B. During outward expansion of each anchor element in its companion cylinder bore 16, the stems 32 of the holding rods 30 are free to slide through the radial bores 33 in the retainer bar 23. To assist in maintaining each holding rod 30 coaxial of its companion bore 33, the head 31 of the rod may have a diameter conforming to the inside diameter of the coil spring 27, so as to snugly engage its inner turns. The springs 27 minimize the opportunity for the holding rods 30 to cock with respect to the bores 33, which might pro- 7 duce a binding action on the stems 32 therewithin.

When the pressure is relieved, the springs 27 reshift the anchor element 15 back to its initial position, there being no restraint whatever ofiered by the holding rods 30, since they are freely slidable in their companion bores 33 in the retainer bar 23. Subsequent application of pressure in the body passage 11 of a value sufficient to overcome the compressive force of thersprings 27 will result in outin the well casing B below the apparatus A, from shifting n the apparatus upwardly and possibly kinking the tubular ward expansion of each anchor element 15 against the wall of the well casing B. ,7

With the releasable holding device illustrated, spring 27 need not be provided of a comparatively heavy section, but only of an ample force to insure return of the anchor elements 15 to retracted position after having been expanded against the wall of the well casing. Premature expansion of each anchor element during lowering of the apparatus to its setting location in the well casing cannot occur because of the positive restraint against'its movement afforded by the holding device 39. It is only when the pressure diiferential within the body passage ll has been increased to a value in excess of the pressures usually developed while running the apparatus in the well casing that the flanges 34 are sheared from the stems 32pto release the holding devices 39 and permit the anchor ele ments '15 to' be shifted hydraulically outwardly against the wall of the well casing B. As 'an example, the, shear flanges-34 may be; disrupted from the stem upon application" of a pressure differential in the central passage 11 of. about 200 psi.

Since the springs '27 are comparatively light, they permit each anchor element 15 to be shifted outwardly to a substantial extent. The use of heavier; springs would result in their being collapsed to solid height with a' comparatively small outward travel of the anchoring element 15. In addition, heavy springs 27 exert a force, counteracting the hydraulic force holding theanchor element 15 tion.

against the wall of the well casing. Although some counteracting force is present in applicants device, the fact that the springs 27 are comparatively light results in the considerable minimizing of such counteracting force.

In the form of invention disclosed in FIGS. and 6, the holding device 30a is essentially the same as the one illusstrated and described in the other form of the invention. However, in lieu of a shear flange or ring 34 integral with the stem 32 being provided, a separate sleeve or ring 40 is mounted on the outer portion of the stem, being secured thereto by a transverse shear pin 41. The ring 40 is at a location in which it bears against the retainer bar 23 with the head 31 engaging the inner face 29 of the anchor element socket 23 to position the anchor element 15 against the body stop shoulders 18. The outer portion of each stem 32 is piloted in a companion guide bore 33 in the retainer and orienting bar 23, and the head 31 on the inner end of the stem 32 preferably makes a snug fit with the inner turns of the helical compression spring 27.

In general, the apparatus disclosed in FIGS. 5 and 6 operates in the same manner as in the other form of the invention. During lowering of the apparatus in the well casing, the restraining and holding device 30a prevents the fluid pressure developed within the body of the tool from shifting the anchor element outwardly. When the setting location in the well casing is reached, the ex ertion of sufficient pressure on the fluid in the body passage 11 causes such pressure to overcome the shear strength of the pin 41, the latter disrupting to free the sleeve or ring 48 from the stem 32, whereupon the fluid pressure can shift the anchor element 15 outwardly against the resisting force of the helical spring or springs 27. The holding device 39;: is no longer efiective to accomplish its holding function. allows the relatively light springs 27 to shift each anchor element 15 back to its retracted position.

In the form of invention shown in FIG. 7, essentially the same holding arrangement is used as in FTGS. 5 and 6. However, instead of a shear pin 41 releasably connecting a sleeve or ring 49 to the stem 32, a shear pin 42 merely extends transversely through the stem 32 and engages the inner side 35 of the piston retainer bar 23. The shear pin 42 is so located as to engage the bar 23 with the holding rod head 31 hearing a ainst the bottom 29 of the socket '28 and locating the anchor element 15 in engagement with the body stop shoulders 18. The shear pins 42 will positively hold each anchor element 15 in its retracted posi- Wnen suflicient pressure is developed'within the body passage 11, such pressure acts on each anchor element 15 to overcome the shear strength of the pins 42, disrupting their outer ends and forcing the anchor element 15 outwardly to place its teeth 19 in anchoring engagement with the wall of the well casing B. During such outward shifting, each stem 32 slides freely through its guiding bore 33 in the retainer bar 23. It is to be noted that the outer end of each holding rod 32 terminates inwardly of the teeth 19 with the gripping element 15 eX- panded so that the rods 32 do not interfere with the embedding of the teeth in the wall of the well casing. This is also true of the positioning of the outer ends of the stems 32 in the other forms of the invention (FIGS. 4

and 6).

In the form of invention illustrated in FIGS. 8 to 10, essentially the same'apparatus is illustrated as in FIGS. 1 to 4, inclusive, except that each releasable restraining or holding rod 3th is made in a plurality of elements adjustably secured to one another. As shown, the stem 32a of the rod 39c has a threaded portion 5% threadedly re- A relieving of the pressure within the tool has an outer slot 53 for reception of a suitable tool, such as a screwdriver (not shown).

The threaded arrangement illustrated in FIGS. 8 to 10 insures a snug contact of the piston gripping member 15 with the body stop shoulders 18 and a snug engagement of the shear ring 34 with the retainer bar 23 when the apparatus is being lowered in the hole. In assembling the apparatus, the stem 32a is threaded into the head 31a and the outer portion of the stem is then inserted into the bore or opening 33 in the retainer bar 23. The spring 27 may then he slipped over the head and stem, and this combination is mounted in appropriate assembled relation with respect to a piston gripping member 15, the piston gripping member then being inserted in its companion cylindrical bore 16, with the piston retainer 23 disposed in the body grooves 25. The screws 26 are then threaded in place to secure the reta ner to the body. With the parts assembled in the manner described, the stem 32:: is not at its final position within the head 31a. The piston anchor gripping member 15 will be urged against the stop shoulders 13 by the springs 27, but the shear ring 34 and the head 31a will not be simultaneously in engagement with the retainer bar 23 and the base 29 of the socket 28, respectively. Accordingly, a suitable screwdriver is inserted in the slot 53 and the stem 3241 turned in the proper direction to feed the stem outwardly of the head 31a, which is prevented from turning by the embracing action of the helical spring 27. The stem will feed outwardly of the head until its shear ring 34 engages the retainer bar 23, after which continued rotation of the stem in the same direction will shift the head 31:: toward and into contact with the base 29 of the socket 28. The simultaneous contact of the shear ring 34 with the retainer bar 23 and of the head 31a with the base 29 of the socket, with the gripping element 15 engaging the shoulders 13, will prevent any looseness or play of the piston gripping element 15 in its companion cylinder 16 during lowering of the apparatus through the fluid in the well bore. The piston 15 can only move outwardly when suflicient pressure is imposed thereon to shear the ring 34, after which it is free to move outwardly, resisted only by the compressive force of the springs 27.

If desired, to insure against inadvertent turning of the stem 32a within the head 31a during lowering of the apparatus in the well bore, a punch or wedge device (not shown) may be inserted in the stem slot 53 and a blow .struck upon it, which will slightly spread the outer end of the stem into gripping engagement with the wall of the retainer bar bore 33. The extent of gripping engagement,

however, will be insufiicient to prevent sliding of the stem 32:: in the bore 33 after the ring 34 has been sheared from the stern itself.

It is, accordingly, apparent that a hydraulic anchor for tubular strings has been provided, in which the retracting springs can be made relatively light and yet pressure surges, and the like, developed in the apparatus during its lowering through the fluid in the well casing are incapable of expanding the anchor elements against the wall of the well casing. Following release of the restraining or holding elements 30, 390, 300, a comparatively light force is presented by the springs 27 resisting hydraulic outward expansion of the anchor elements 15 against the wall of the well casing. Being comparatively light, the wire of the springs can be of smaller crosssection, which allows the button elements to be expanded over a wider range than when a heavier spring is used. Following release of the holding devices, they no longer afford any restraint to-movement of the anchor elements either in an outward or an inward direction, the springs, despite being comparatively light, still having slnficient force to insure full retraction of the anchor elements 15 within the confines of the body 10 of the tool. The apparatus is easy to assemble and is comparatively economical to produce. The holding devices 36, Bila, 360 can be made of any suitable material, as, for example, aluminum.

I claim:

1. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding device between and bearing against said members to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position, said device including re leasable means engaging one of said members and releasable by said gripping member when said gripping member is subjected to a predetermined fluid pressure in said passage to allow lateral outward expansion of said gripping member.

2. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding device between and bearing against said members to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position, said device including releasable means engaging one of said members and releasable by said gripping member when said gripping member is subjected to a predetermined fluid pressure in said passage to allow lateral outward expansion of said gripping member; and means for shifting said gripping member from expanded position to retracted position.

3. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said-opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding device between and bearing against said members to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position, said device including releasable means engaging said retainer member and releasable by said gripping member when said gripping member is subjected to a predetermined fluid pressure in :said passage to allow lateral outward expansion of said gripping member.

4. In apparatus to, be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the, well conduit; 'a retaining member mounted on said body; a holding device between and bearing against said members to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position, said device including releasable means, engaging said retainer member and re leasable by'said gripping member when said gripping member is subjected to a predetermined fluid pressure in ,said passage'to allow lateral outward expansion of said gripping member; and means for shifting said gripping member from expanded position to retracted position.

5. Inapparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a: gripping member movable laterally in'said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member;

mountedon said body; a holding device between andbearagainst said members to prevent lateral outward movement of said" gripping member and to holdsaid gripping member in retracted position, said device includ ing frangible means engaging' oneof saidmembers and 8 .member is subjected to a predetermined fluid pressure in said passage to allow lateral outward expansion of said gripping member.

6. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding device between and bearing against said members to prevent lateral outward movement of said gripping member and to hold said gn'p- V ping member in retracted position, said device including frangible means engaging said retainer member and disruptable by said gripping member when said gripping member is subjected to a predetermined fluid pressure in said passage to allow lateral outward expansion of said gripping member.

7. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding rod bearing against one of said members and slidable in an opening in the other of said members; releasable means securbed to said rod and engaging said other of said members to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, releasing said releasable means which permits lateral outwardiexpansion of said gripping member.

8. In apparatus to be lowered in a well'conduit: a

body having a fluid passage and a lateral opening in the Y.

7 other of said members; frangible means secured to said gaging said retaining member to: prevent lateral outward rod and engaging said other of said members to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, disrupting said frangible eans which permits lateral outward expansion of said gripping member. a f

9. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member .mounted on said body; a holding rod bearing against said gripping member and slidable 'in'an opening in said retaining member; releasable means secured to said rod and enmovement of said gripping member and to hold said gripping member inretracted position; said gripping member,

when acted upon'by a predetermined fluid pressure in said passage, releasing said releasable means which permits lateral outward expansion of saidgrippin'g member.

10. In apparatus to be loweredtin a well'conduit: a fbody having a fluid passage and a'lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the Well conduit; a retaining member mounted on said body; a holding rod bearing against said gripping member andslidable in an opening in" said retaining member; frangible means secured to'said rod and disruptable by saidegripping member when said gripping en aging said retaining member to prevent lateraloutward "movement of said gripping member and to hold said gripping member in retracted position; said gripping member,

when acted upon by a predetermined fluid pressure in said passage, disrupting said frangible means which permits lateral outward expansion of said gripping member.

11. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding rod bearing against one of said members and slidable in an opening inthe other of said members; a shearable flange integral with said rod and engaging said other of said members to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, shearing said flange from said rod which permits lateral outward expansion of said gripping member.

12. In apparatus to-be lowered in a well conduit: a body having a .fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding rod bearing against said gripping member and slidable in an opening in said retaining member; a flange integral with said rod and engaging said retaining member to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, shearing said flange from said rod which permits lateral outward expansion of said gripping member.

13. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding rod bearing against one of said members and slidable in an opening in the other of said members; a ring mounted on said rod; frangible means securing said ring to said rod with said ring engaging said other of said members to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, disrupting said frangible means which permits lateral outward expansion of said gripping member.

14. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit; a retaining member mounted on said body; a holding rod bearing against one of said members and slidable in an opening in the other of said members; a ring mounted on said rod and engaging said retaining member; a shear pin securing said ring to said rod, whereby said ring bears against said retaining member and said rod against said gripping member to prevent lateral outward movement of said gripping member to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, shearing said pin which permits lateral outward expansion of said gripping member.

15. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into grip- 10 v ping engagement with the well conduit, said gripping member having a slot in its outer portion; a retainer member mounted on said body and extending into said slot; a helical spring in said slot bearing against said retaining member and gripping member to urge said gripping mem ber inwardly of said body to retracted position; a rod within said spring bearing against said gripping member and slidable in an opening in said retaining member; frangible means secured to said rod and engaging said retaining member to prevent lateral outward movement of said gripping member to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, disrupting said fiangible means which permits lateral outward expansion of said gripping member.

16. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiflable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit, said gripping member having a slot in its outer portion; a retainer member mounted on said body and extending into said slot; a helical spring in said slot bearing against said retaining member and gripping member to urge said gripping member inwardly of said body to retracted position; a rod within said spring bearing against said gripping member and slidable in an opening in said retaining mem ber; a flange integral with said rod engaging said retaining member to prevent lateral outward movement of said gripping member to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, shearing said flange from said rod to permit lateral outward expansion of said gripping member.

17. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit, said gripping member having a slot in its outer portion; a retainer member mounted on said body and extending into said slot; a helical spring in said slot bearing against said retaining member and gripping member to urge said gripping mem ber inwardly of said body to retracted position; a rod within said spring bearing against said gripping member and slidable in an opening in said retaining member; a ring on said rod engaging said retaining member; a shear pin securing said ring to said rod with said ring engaging said retaining member and said rod engaging said gripping member to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, disrupting said shear pin to permit lateral outward expansion of said gripping member.

18. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the body communicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit, said gripping member having a slot in its outer portion; a retainer member mounted on said body and extending into said slot; a helical spring in said slot bearing against said retaining member and gripping member to urge said gripping member inwardly of said body' to retracted position; a holding rod in said spring and having an inner head engaging said gripping member, said head having a diameter conforming to the inside diameter of said spring; said retaining member having a hole in which said rod is slidable; frangible means on said rod engaging said retaining member to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted 11 position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, disrupting said frangible means to permit lateral outward expansion of said gn'pping member.

19. In apparatus to be lowered in a well conduit: a a

body having a fluid passage and a lateral opening in the body communicating :with said passage; a gripping memto the inside diameter of said spring; said retaining member having a hole in which said rod is slidable; a flange integral with said rod and engaging said retaining member to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted position; said gripping member, when acted upon by a predetermined fluid pressure in said passage, shearing said flange from said rod to permit lateral outward expansion of said gripping member.

20. In apparatus to be lowered in a well conduit: a body having a fluid passage and a lateral opening in the bodycomtmunicating with said passage; a gripping member movable laterally in said opening and shiftable by the pressure of fluid in said passage outwardly into gripping engagement with the well conduit, said gripping member having a slot in its outer portion; a retainer member mounted on said body and extending into said slot; a helical spring in said slot bearing against said retaining member and gripping member to urge said gripping member inward-1y of said body to retracted position; a holding rod in said spring and having an inner head engaging said gripping member, said head having a diameter conforming to the inside diameter of said spring; said retaining member having a hole in which said rodis slidable; a ring on said rod engaging said retaining member; a shear pin securing said ring to said rod with said ring engaging said retaining member and said head engaging said gripping member to prevent lateral outward movement of said gripping member and to hold said gripping member in retracted positionysaid gripping member, when acted upon by a predetermined fluid pressure in said passage, shearing said pin to permit lateral outward expansion of said gripping member.

References Cited in the file of this patent UNITED STATES PATENTS Jones May 14, 1957 Baker et al. v Mar. 12, 1963 

1. IN APPARATUS TO BE LOWERED IN A WELL CONDUIT: A BODY HAVING A FLUID PASSAGE AND A LATERAL OPENING IN THE BODY COMMUNICATING WITH SAID PASSAGE; A GRIPPING MEMBER MOVABLE LATERALLY IN SAID OPENING AND SHIFTABLE BY THE PRESSURE OF FLUID IN SAID PASSAGE OUTWARDLY INTO GRIPPING ENGAGEMENT WITH THE WELL CONDUIT; A RETAINING MEMBER MOUNTED ON SAID BODY; A HOLDING DEVICE BETWEEN AND BEARING AGAINST SAID MEMBERS TO PREVENT LATERAL OUTWARD MOVEMENT OF SAID GRIPPING MEMBER AND TO HOLD SAID GRIPPING MEMBER IN RETRACTED POSITION, SAID DEVICE INCLUDING RELEASABLE MEANS ENGAGING ONE OF SAID MEMBERS AND RELEASABLE BY SAID GRIPPING MEMBER WHEN SAID GRIPPING MEMBER IS SUBJECTED TO A PREDETERMINED FLUID PRESSURE IN SAID PASSAGE TO ALLOW LATERAL OUTWARD EXPANSION OF SAID GRIPPING MEMBER. 